There is no substitute for having a tube tester "in house" to try to figure out why the glow went away at 9 p.m. on a Saturday.
Check Ebay under "tube tester". A tester for every budget. For quick and dirty testing (cheap to) I would suggest a Eico 667 ($30-90). Faster and easlier, a BK 600 or 700 series ($50-200). These testers will ID dead and dying tubes and will enable you to do rough matching of pairs.
These are not Hickoks but will do the job.
If you want the cream de la cream there is always a Hickok 539(c) for $500-1000. If you are going to spend big bucks make sure that the unit has been calibrated.
Check Ebay under "tube tester". A tester for every budget. For quick and dirty testing (cheap to) I would suggest a Eico 667 ($30-90). Faster and easlier, a BK 600 or 700 series ($50-200). These testers will ID dead and dying tubes and will enable you to do rough matching of pairs.
These are not Hickoks but will do the job.
If you want the cream de la cream there is always a Hickok 539(c) for $500-1000. If you are going to spend big bucks make sure that the unit has been calibrated.